Philbrick Research P65 OPAMP From 1962

 

This has got to be the longest I have ever procrastinated on any project! I ‘Saved’ this Philbrick P65 OPAMP from a Dumpster in about 1980 and I have treasured it ever since then. I mean who wouldn’t want a little discrete OPAMP in a nice cardboard box, and housed in a shiny metal case?

Finally, I have powered it up and tested it. And..... Yes, it still works. Did you think it wouldn’t?

The Presentation:

The George A. Philbrick Research (GAP/R) P65 came in a fine little cardboard box with a nice enameled black label. Inside is a neatly folded data sheet on top of the P65 itself, which is kept in place by little cardboard tabs (See figures below).

The P65 itself was billed as,

“Model P65 is an all silicon solid-state unit designed for applications in instrumentation, computing, and control where plug-in versatility, low cost, long life, low power consumption, low noise, and operation at any temperature from -25°C to +85°C are desirable.”

I’m not sure exactly when this unit was made or purchased, but the date on the datasheet says 1962.

An “All Silicon” amplifier was cutting edge, and more expensive in 1962 as there was still a lot of Germanium floating around then.

I powered the unit up and not surprisingly, the OPAMP still works. I checked a lot of the specs on the datasheet, and did some tests on loop gain, step response, and noise. The P65 all pretty much works today just like it did in 1962.

As can be seen from the board topside photo below, it is a mix of Texas Instruments, I think the “Diamond N” logo is the old Panasonic house brand ‘National’ (I may be wrong, it may be National Semiconductor) and there is another logo that I can’t quite make out, it’s red - whatever it is, so we will just call it TI also. 

Conclusion:

The first transistors I ever ran into were from really old radios and they were in metal cans that had Phenolic headers, I doubt that any of them work anymore as the Phenolic wasn’t a very good hermetic seal, these transistors are sealed well enough to have lasted from the 1960s and still operate.

Now I guess I have to go out and buy three or four more of these to make some sort of Analog Computer out of them. That's the way it always is: One thing leads to another.

Perhaps it would have been best if I hadn't powered on the P65 on after all! 

Figures:

 

Data Sheet Page 1

 

 

Data Sheet Page 2

  

Box Outside

 

Box Inside - Showing how data sheet is supplied.

  

Box Inside - Showing P65 in its little nest

  

Box Inside - P65 Removed, empty box

  

P65 - Top - The Offset Trim adjustment screw hole is on the opposite side.

  

P65 - Bottom - Trim Adjustment screw hole is on the top of this picture.

 

P65 - Side view with side cover removed. The side covers were tacked in place with solder. You can see the Trimpot pointing out the side inside the unit.

 

P65 - PCB Top - Yes that is a Offset Trim Adjustment Potentiometer. At a Gain of 10, It was easy to adjust the P65 to less than 1 mV offset using the Potentiometer.

 

P65 - PCB Bottom - The solder joints still looked nice and shiny.

 

P65 - Large Step Response AV=10, Red = Output, Blue = Input

 

P65 - Small Signal Step Response AV=10, Red = Output, Blue = Input

 

P65 - Closed Loop Gain Measurement AV=10, & AV=1. Just about the same as a LM741 which was designed in 1968.

 

P65 - Input Noise Voltage Measurement - Not too bad for 1962 - 18 nV/rt-Hz > 1000 Hz

Not shown but measured: I measured the Full Power Bandwidth and with 20Vp-p output the P65 easily met the 10 kHz specification.

References:

All of the documentation on the P65 here has been placed at the Internet Archive,
https://archive.org/details/philbrick-p-65-opamp


Also see the Philbrick Archive for a lot of other Philbrick information including some magazine advertisements for the P65 at,

https://philbrickarchive.org/

Article By: Steve Hageman www.AnalogHome.com    

We design custom: Analog, RF and Embedded systems for a wide variety of industrial and commercial clients. Please feel free to contact us if we can help on your next project. 

This Blog does not use cookies (other than the edible ones).